Researchers at National Chi Nan University have reported that Osmanthus fragrans may inhibit the action of tyrosinase. The research team, led by Li-chen Wu, published these findings in LWT-Food Science and Technology, the official journal of the Swiss Society of Food Science and Technology.

While the Chinese plant is a common flavor additive for tea and other beverages, the researchers found it may have potential applications in biomedical science. They investigated O. fragrans acetonic extract (OFE) for its total phenolic and flavonoid contents, radical-scavenging activity and potential anti-tyrosinase ability.

The researchers reported that OFE possessed considerable amounts of phenolics and flavonoids. The antioxidation activities, measured in terms of EC50 values using DPPH and ABTS+ assays, were 304.9 mg ascorbic acid equivalent/g of extract and 516.3 mg trolox equivalent/g of extract, respectively. The results showed the presence of luteolin in the extract, and a kinetic study revealed an uncompetitive inhibitory effect of OFE upon the oxidation of tyrosine (IC50 = 2.314 mg/mL) and l-DOPA (IC50 = 44.20 mg/mL).

The researchers tested OFE in vitro for its anti-tyrosinase activity and anti-melanin formation and found that OFE was able to reduce the tyrosinase activity and melanin formation of B16F10 cells in a dose-dependent manner.

The study concluded that O. fragrans is a potential natural, functional antioxidant food flavor additive and that, due to its inhibition of melanin formation, it may have potential as an anti-browning food additive, in skin-whitening cosmetics, or as a new drug to treat melanoma.